JMON is a machine language monitor program I wrote for the Briel Replica 1, a replica of the Apple 1. It was only natural to want to port it to run on my new Superboard ///. Given that both computers use a 6502 microprocessor, and JMON has minimal hardware dependencies, it was not hard to do. In one evening I had it all working on the Superboard ///.
After determining the addresses of suitable keyboard input and screen output routines, I very quickly got it up and running. Most of the work to fully port it was to adapt the output to the smaller screen width (24 characters) of the Superboard. I also had to disable some features that did not apply. It is now fully working and is quite useful, particularly as the built-in OSI machine language monitor is very primitive.
Years ago, when I had an original Superboard II, I wrote some machine language programs by hand assembling them and entering the hex codes into the monitor. I very quickly wrote a disassembler in BASIC in order to help verify and debug my programs.
JMON is cross-compiled on a desktop computer, and both the Apple Replica 1 and Superboard /// versions build from the same source code using ifdefs for conditional code.
Below are some representative screens showing some of the commands.
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| Initial Screen |
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| Help command |
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| Disassemble command |
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| Memory Dump command |
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| Info command |
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| Changing registers and single stepping |
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| Memory test |
